Piston lock



2 Sheets-Sheet 1 INVENTOR.

F. HALWARD PISTON LOCK Filed April 17. 1948 Dec. 5, 1950 F. HALwARD 2,532,768

PIsToN Loox Filed April 17. 1948 2 Sheets-Sheet 2 Hl 725 M f Q 27- T I SM Y@ M,

Ff-'1&4

INVENTOR.

ATTORNBS engage the chamfered faces of the blocks 9, the Y pressure is greatly multiplied. For example, I find that Awith a 5 angle of the faces of the blocks, the mechanical advantage afforded at this angle Iwould provide an additional pressure of A 57,150 lbs. to the normal pressure of 12,566 lbs., making a total pressure of 69,716 lbs. resisting the separation of the dies. With a 7 angle of the faces of the blocks, the mechanical advantage aiforded would provide an additional pressure of 40,721 lbs. to the normal pressure of 12,556 lbs. making a total pressure of 53,287 lbs. resisting the separation of the dies. angle of the faces of the blocks, the mechanical advantage afforded would provide an additional pressure of 28,355 lbs. to the normal pressure of 12,566 lbs'. making a total pressure of 40,921 lbs. resisting the separation of the dies. Withva angle of the faces of the blocks, the mechanical advantage afforded would provide an additional pressure of 18,660 lbs. to the normal pressure of 12,566 lbs., making a total pressure of 31,226 lbs. resisting the separation of the dies.

The. apparatus operates as follows: when the slide valve I3 has the Vvalve operating lever I4 thrown to the right the pressure source pipe I5 is connected with the pipe I6 which connects with the top of the cylinder. Piston 2 and 3 is caused to move downwardly in the cylinder. This cylinder has locking annular recess II near the bottom and in this is the hardened ring 9. Valve I8 is normally completely closed by spring I9 that operates against =a head on the lower end of valve stem 2I. This condition of valve I8 is shown in Figure l. When the lower head 20 of the valve strikes the bottom of the cylinder as shown in Figure 5 valve I8 is pushed open and passageway 22 is now open to the pressure iuid above the piston. This passageway 22 leads to the chamber 23 between the slides 6 and 6A, consequently, the uid pressure pushes these slides apart as shown in Figure 5 with all the pressure that is in the fluid line. This Acauses the chamfered surfaces 'I on the upper portions and at the ends of the sliding blocks to wedge in contact with the undercut angular surfaces 8` of the ring segments and rmly lock the segments in place and also lock the piston against any pressure coming through the piston rod 24 reversing the direction of the piston. With this piston rod 24 is connected with a movable die holder or carrier even such great pressure as obtained in some die casting operations will not and cannot reverse the movement of the piston. The piston is -rmly locked and the dies are held rmly together.

'r To reverse the movement of the piston and unlock the same it is only necessary to throw the lever Il to the left as shown in Figure 4, this connects the source of fluid pressure I6 to pipe 25. Thisestablishes pressure in the clearance space 26. At the ends of the sliding locking blocks this causesthe blocks to retreatY inwardly to the position shown in Figure i at which point the cylindrical ends of each block has considerable clearance with respect to the cylinder wall, further movement of the slides together is blocked by the head 2'I` of the valve 23 being jammedbetween the two blocks at their-inner ends.l As shown in Fig'- With a 10 ure 4 valve 28 is open and when the locking blocks or slides are in their inner position. Passageway 29 guarded by valve 2-8 now registers with passageway 30 leading to the bottom of the piston and the fluid pressure is now furnished to the bottom of the piston `and will lift the piston to its uppermost position.

By having valve 28 the uid pressure does not reach passage 30 and the bottom of the cylinder to lift the piston until the slides or blocks have been completely withdrawn into the piston and the piston is free to lift.

What I claim is:

1. A pressure iiuid servo-motor having in combination, a cylinder, a piston reciprocating in the cylinder and means for locking the piston at one end of its stroke comprising a pressure chamber on the piston and a lockingY block forced out of the piston by fluid pressure admitted to said chamber into engagement with the wall structure of the cylinder when the piston has reached the limit of its motion, a valve located in the piston guarding a passageway into the piston and to the chamber containing said block, the said valve automatically tripped when the piston reaches the limit of its movement to allow fluid pressure to flow into the chamber to throw the block out into engagement with the wall structure of the cylinder.

2. A pressure fluid servo-motor having in combination, la cylinder, a, piston reciprocating in the cylinder and means for locking the piston at one end of its stroke comprising a pressure -chamber on the piston' and a locking block forced out of thepiston by fluid pressure admitted to said chamber into engagement with Vthe wall structure of the cylinder when the piston has reached the limit of its motion, a valve located in the piston guarding a passageway into the piston' and to the chamber containing said block, the said valve automatically tripped when the piston reaches the limit of its movement to allow fluid pressure to iiow into the chamber to throw the block out into engagement with the `wall structure of the cylinder, a second passageway from a controlled source of fluid pressure to the piston fand through said block, said passage allowing uid under pressure to engage the block to cause the same to retreat into the piston, a passageway through the piston with which the passage through the block registers when the block isvin retreat allowing pressure to get behind the piston to reverse the movement. Y

.3. A pressure fluid servo-motor having in coinvbination, a cylinder, a piston reciprocating in the cylinder and means for locking the piston at one end of its stroke comprising a pressure chamber on the piston and a locking block forced out of the piston by fluid prfssure admitted to said chamber into engagement lwith the wall structure of. the cylinder when the piston has reached the limit of its motion, a valve located in the piston guarding a passageway into the piston and to the chamber containing said block, the said valve automatically tripped when the piston reaches the limit of its movement to allow uid pressure to ow into the chamb^r to throw the block out into engagement with the wall structure of the cylinder, a second passageway from a controlled sour-ce of fluid pressure to the piston and through said block, said passage c llowing duid under pressure to engage the block to cause the same to retreat ,into the piston, a passageway through the piston with which the passage through the block registers when the block is in retreat allowing pressure to get behind the piston to reverse the movement and `a valve guarding the passage through the block and opened when the block has retreated into the piston.

4, A pressure iiuid servo-motor having in combination, a cylinder, a piston reciprocating in the cylinder and means for locking the piston at one end of its stroke comprising a pressure chamber on the piston and a locking block forced out of the piston by fluid pressure admitted to said chamber into engagement with the wall structure of the cylinder when the piston has reached the limit of its motion, a valve located in the piston guarding a passageway into the piston and to the chamber containing said block, the said valve automatically tripped when the piston reaches the limit of its movement to allow uid pressure to flow into the chamber to throw the block out into engagement with the wall structure of the cylinder, a second passageway from a controlled source of fluid pressure to the piston and through said block, said passage allowing fluid under pressure to engage the block to cause the same to retreat into the piston, a passageway through the piston with which the passage through the block registers "when the block is in retreat allowing pressure to get behind the piston to reverse the movement and a valve guarding the passage through the block and opened when the block has retreated into the piston, the rst mentioned valve having la head on the outer end of the piston guarding the passageway into the chamber behind the block and having a stem extending clear through the piston to be engaged by the end wall of the cylinder thereby lifting the valve head off its seat when the piston reaches the bottom of the cylinder.

5. A pressure fluid servo-motor having in combination, a cylinder, a piston reciprocating in the cylinder and means for locking the piston at one end of its stroke comprising a pressure chamber on the piston and a locking block forced out of the piston by uid pressure admitted to said chamber into engagement with the wall structure of the cylinder when the piston has reached the limit of its motion, a valve located in the piston guarding a passageway into the piston and to the chamber containing said block, the said valve automatically tripped when the piston reaches the limit of its movement to allow fluid pressure to flow into the chamber to throw the block out into engagement with the wall structure of the cylinder, the irst mentioned valve having a head at the outer end of the piston guarding the passageway into the chamber behind the block and having a stem extending clear through the piston to be engaged by the end wall of the cylinder thereby lifting the valve head off its seat when the piston reaches the bottom of the cylinder.

6. A pressure fluid servo-motor having in combination, a cylinder, a piston reciprocating in the cylinder and means for locking the piston at one end of its stroke comprising a pressure chamber on the piston a locking block forced out of the piston by iiuid pressure admitted to said chamber into engagement with the wall structure of the cylinder when the piston has reached the limit of its motion, a valve located in the piston guarding a passageway into the piston and to the chamber containing said block, the said valve automatically tripped when the piston reaches the limit of its movement to allow iluid pressure to flow into the chamber to throw the block out into engagement with the wall structure of the cylinder, the said block provided with a passageway passing through the side thereof :and then through the face thereof and said piston provided r with a passageway adapted to register with the passageway through the sliding block when the block is driven in by the pressure fluid and to thereby admit fluid under pressure to the underside of the piston to reverse the movement.

7. A pressure fluid servo-motor having in combination, a cylinder, a piston reciprocating in the cylinder and means for locking the piston at one end of its stroke comprising a pressure chamber on the piston and a locking block forced out of the piston by iiuid pressure admitted to said chamber into engagement with the wall structure of the cylinder when the piston has reached the limit of its motion, a valve located in the piston guarding a passageway into the piston and to the chamber containing said block,l the said valve automatically tripped when the piston reaches the limit of its movement to allow fluid pressure t0 flow into the chamber to throw the block out into engagement with the wall structure of the cylinder, the said block provided with a passageway passing through the side thereof and then through the face thereof and said piston provided with a passageway adapted to register with the passageway through the sliding block when the block is driven in by the pressure iiuid and to thereby admit iluid under pressure to the underside of the piston to reverse the movement, the said passageway through the block being guarded by a valve which is closed when the block is projected and which valve is automatically opened when the block is in its position of retreat and which then allows passage of the fluid through the passageway in the block and then through the passageway in the piston to the end of the piston to reverse its movement.

FOLKE HALWARD.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,183,213 Lewis May 16, 1916 1,650,013 Gartin Nov. 22, 1927 1,842,776 Bogoslowsky Jan. 26, 1932 2,204,279 Meyer June 11, 1940 2,282,297 Keller May 5, 194:2,y 2,342,812 Martinson Feb. 29, 1944 

